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Background: Platycladus orientalis (L.) Franco (PO) has been used in Oriental medicine to treat rheumatism and diarrhea; however, its antinociceptive effects remain unclear. Objective: This study aimed to reveal the antinociceptive effect of the PO extract and standardize this extract in RAW 264.7 cells and mice with monosodium uric acid (MSU)-induced pain. Results: PO extracts were prepared using different ethanol (EtOH) concentrations (0–100%). Thereafter, groups were determined based on the results of the MSU-induced pain model in mice and nitric oxide (NO) assay using lipopolysaccharide (LPS)-induced RAW 264.7 cells. As the methylene chloride (CH2Cl2) and ethyl acetate (EtOAc) layers exhibited increasing effects with time, these layers were selected to isolate the major components. The PO extract was standardized using a highly efficient HPLC method, and its antinociceptive effects in a mouse model of MSU-induced gout pain were determined using the von Frey test. The PO extract was found to exhibit antinociceptive effects. Moreover, sample standardization was successfully achieved based on the validation of these compounds. Conclusion: The PO extract exhibited potent dose- and time-dependent antinociceptive effects in an animal model of gout pain; these effects might be mediated by the major compounds of this extract. Collectively, these results suggest that PO can be used as a herbal drug to treat gout-related pain. [ABSTRACT FROM AUTHOR]

Objective To investigate the anti-inflammatory and antinociceptive effects and acute toxicity of the ethyl acetate fraction (FPEA) from the 95% ethanol extraction of Fissistigma polyanthum (FPEE) in vivo. Methods Observation of anti-inflammatory effects: ICR mice were randomly divided into the blank control group, model group, positive group, and low-, medium-, and high-dose FPEA groups. Mice in low-, medium-, and high-dose FPEA groups were gavaged with 200, 400, and 800 mg/kg of FPEA, respectively. Mice in the positive group were gavaged with dexamethasone, while mice in the blank control group and model group were gavaged with equal volume of normal saline. Mice were treated daily for five consecutive days. Except for the blank control group, the right hind paw of each mouse was subcutane⁃ ously injected with carrageenan to induce edema. The paw volume was measured at 1, 2, 3, 4, 5, and 6 h after the injec⁃ tion, then the edema degree and the inhibition rate of paw edema were calculated. The levels interleukin-1β（IL-1β), IL6, and tumor necrosis factor-α（TNF-α) in serum of the mice at 6 h after the injection were measured by ELISA. ICR mice were randomly divided into model group, positive group, and low-, medium-, and high-dose FPEA groups, and mice in each group were treated with the same methods as above. The ear edema degree and the inhibition rate of ear edema were calculated using the xylene-induced ear edema model. Observation of antinociceptive effects: ICR mice were randomly divided into the model group, positive group, and low-, medium-, and high-dose FPEA groups. Mice in each group were treated with the same methods as described above, but mice in the positive group were treated with the aspirin and Yuanhu Zhitong tablets. Each mouse was given an intraperitoneal injection of acetic acid, then the number of abdominal writhing was recorded for 30 min and the inhibition rate of writhing was calculated. The latency time was determined at 30, 60, 90, and 120 min after the drug administration. Observation of acute toxicity: ICR mice were randomly divided into the blank control group, FPEE group, and FPEA group (half male and half female). Mice in the FPEE group and FPEA group were gavaged with FPEE and FPEA at a dose of 2000 mg/kg, respective, while mice in the blank control group were gavaged with equal volume of normal saline. The body weight of mice were recorded within 14 days after intragastric administration. At the end of the observation, all mice were sacrificed, then the organ indexes of heart, liver, spleen, lung, kidney, and thymus were calculated. Results Compared with the model group, the paw edema degree of mice in the positive group were reduced at 4, 5, and 6 h after the induction of inflammation, and the paw edema degree of mice in mediumand high-dose FPEA groups were reduced at 5 and 6 h after the induction of inflammation (all P<0. 05). At 6 h after the in⁃ duction of inflammation, there was no significant difference in the inhibition rate of paw edema between the high-dose FPEA and positive groups (P>0. 05). The levels of IL-1β, IL-6, and TNF-α in serum of the model group were higher than those of the blank control group, the levels of IL-6 and TNF-α in the positive group and low-, medium-, and high-dose FPEA groups were lower than those of the model group, and the level of IL-1β in the positive group and medium- and high-dose FPEA groups were lower than those of the model group (all P<0. 05). The ear edema degree were lower in the positive group and low-, medium-, and high-dose FPEA groups than in the model group (all P<0. 05), and there was no significant difference in the in the inhibition rate of ear edema between the medium- and high-dose FPEA groups and the positive group (all P>0. 05). The writhing times of mice in the positive group and low-, medium-, and high-dose FPEA groups were less than those in the model group, and the inhibition rates of writhing in low-, medium-, and high-dose FPEA groups were less than that of the positive group (all P < 0. 05). The latency time at 60, 90, and 120 min in the positive group and low-, medium-, and high-dose FPEA groups were longer than that of the model group (P<0. 05). There was no significant difference in the body weight or organ indexes of heart, liver, spleen, lung, kidney, and thymus between the treated (at the dose of 2000 mg/kg) and the blank control groups (all P>0. 05). Conclusion The FPEA exhibited better anti-inflammatory and antinociceptive effects, and did not show acute toxicity [ABSTRACT FROM AUTHOR]

Oral squamous cell carcinoma (OSCC) presents significant treatment challenges due to its poor survival and intense pain at the primary cancer site. Cancer pain is debilitating, contributes to diminished quality of life, and causes opioid tolerance. The stimulator of interferon genes (STING) agonism has been investigated as an anti-cancer strategy. We have developed STINGel, an extended-release formulation that prolongs the availability of STING agonists, which has demonstrated an enhanced anti-tumor effect in OSCC compared to STING agonist injection. This study investigates the impact of intra-tumoral STINGel on OSCC-induced pain using two separate OSCC models and nociceptive behavioral assays. Intra-tumoral STINGel significantly reduced mechanical allodynia in the orofacial cancer model and alleviated thermal and mechanical hyperalgesia in the hind paw model. To determine the cellular signaling cascade contributing to the antinociceptive effect, we performed an in-depth analysis of immune cell populations via single-cell RNA-seq. We demonstrated an increase in M1-like macrophages and N1-like neutrophils after STINGel treatment. The identified regulatory pathways controlled immune response activation, myeloid cell differentiation, and cytoplasmic translation. Functional pathway analysis demonstrated the suppression of translation at neuron synapses and the negative regulation of neuron projection development in M2-like macrophages after STINGel treatment. Importantly, STINGel treatment upregulated TGF-β pathway signaling between various cell populations and peripheral nervous system (PNS) macrophages and enhanced TGF-β signaling within the PNS itself. Overall, this study sheds light on the mechanisms underlying STINGel-mediated antinociception and anti-tumorigenic impact. [ABSTRACT FROM AUTHOR]

Clinically, neuropathic pain treatment remains a challenging issue because the major therapy, centred around pharmacological intervention, is not satisfactory enough to patient by reason of low effectiveness and more adverse reaction. Therefore, it is still necessary to find more effective and safe therapy to ameliorate neuropathic pain. The purpose of this study was to explore the antinociceptive effect of Echinacoside (ECH), an active compound of Cistanche deserticola Ma, on peripheral neuropathic pain induced by chronic constriction injury (CCI) in mice, and to demonstrate its potential mechanism in vivo and vitro. In the present study, results showed that intraperitoneal administration of ECH (50, 100, and 200 mg/kg) could alleviate mechanical allodynia, cold allodynia and thermal hyperalgesia via behavioural test. Moreover, the structure and function of injured sciatic nerve by CCI were taken a turn for the better to a certain extent after ECH treatment using histopathological and electrophysiological test. Furthermore, ECH repressed the expression of the P2X7R and FKN and reduced the expression and release of the IL-1β, IL-6 and TNF-α. Besides, ECH could decrease Ca2+ influx and Cats efflux and inhibit phosphorylation of p38MAPK. To sum up, the present study illustrated that ECH could alleviate peripheral neuropathic pain by inhibiting microglia overactivation and inflammation through P2X7R/FKN/CX3CR1 signalling pathway in spinal cord. This study would provide a new perspective and strategy for the pharmacological treatment on neuropathic pain.

The new synthetic anti-inflammatory agent, 4-(5'-dimethylamino)-naphthalenesulfonyl-2(3H)-benzoxazolone (W3D), has demonstrated definite biological activity both in vitro and in vivo. In this study, we investigated the antinociceptive effects of W3D on various animal pain models. Our results showed that W3D, at doses of 12.5 and 25 mg/kg, significantly reduced acetic acidinduced mice writhing by 65.9% and inhibited the pain response in the second phase of formalin-induced pain from 167.75 ± 6.76 s to 97.25 ±9.63 s. Moreover, W3D prolonged the latent period on the tail-immersion test, which was stronger than the positive drug, aspirin (50 mg/kg). However, W3D did not show analgesic activity on the hot plate test, indicating no central pain response. Furthermore, the antinociceptive effects of W3D were not antagonized by naloxone, EGTA, CaCl2, and reserpine. However, LArginine was able to reverse the antinociceptive effect, indicating that W3D's antinociceptive effect does not depend on opioid receptors, Ca2+ concentration, or monoamine content. Instead, it is closely associated with nitric oxide (NO) content. In addition, W3D was found to alleviate nocifensive behavior and improve brain histopathology by inhibiting NO, inducible nitric oxide synthase (iNOS), and calcitonin gene-related peptide in nitroglycerin-induced migraine mice, with more than 50% inhibition ratio at only 12.5 mg/kg orally. However, noradrenaline, dopamine, and 5-hydroxytryptamine levels were not significantly altered after treatment with W3D. In conclusion, the presented data suggest that W3D can be considered a new non-steroidal anti-inflammatory and antinociceptive agent for the treatment of peripheral pain and migraine mediated by NO and iNOS. [ABSTRACT FROM AUTHOR]

Objective To research the analgesic effect of galanin on native rats, inflammatory rats and neuropathic rats in nucleus accumbens (NAc), and to explore its mechanism. Methods　A inflammatory pain model was prepared by subcutaneous injection of carrageine into rat’s plantar, while the model of neuralgia was prepared by ligation of the left sciatic nerve. The hind-paw withdraw latency (HWL)induced by thermal stimulation and the hind-paw withdraw threshold (HWT)induced by mechanical stimulation were measured to reflect the pain threshold. The expression of galanin receptors (GalRs) in the nucleus accumbens of inflammatory and neuropathic rats were detected by western blot ( WB). Results 1. The HWL of normal ( Pleft < 0.05; Pright < 0.01), inflammatory (Pleft < 0.001; Pright < 0.001)and neuropathic (Pleft < 0.001; Pright < 0.001) rats were increased by injection of galanin into nucleus accumbens, and the HWT of normal (Pleft < 0.001; Pright < 0.01), inflammatory (Pleft < 0.001; Pright < 0.001)and neuropathic (Pleft < 0.001; Pright < 0.001) rats also were increased. 2. The antinociception of galanin on the rats with inflammatory (HWL: Pleft < 0.05, Pright < 0.05; HWT: Pleft < 0.01, Pright < 0.05)or neuropathic pain (HWL: Pleft < 0.05, Pright < 0.05; HWT: Pleft < 0.001, Pright < 0.001)was stronger than that of the native rats. However, the antinociception of galanin on the rats with the inflammatory pain and neuropathic pain was not significantly different (P > 0.05). 3. The expressions of GalR1 were increased in rats after 3 hours of subcutaneous injection of carrageine (P < 0.001) and 14 days of sciatic nerve ligation (P < 0.001), and the expressions of GalR2 also were increased in rats after 3 hours of subcutaneous injection of carrageine (P < 0.05) and 14 days of sciatic nerve ligation ( P < 0.05). Conclusion Intra-NAc injection of galanin has the antinociceptive effects on native, inflammatory and neuralgia rats and the antinociceptive effect of galanin in rats is induced by the activation of GalRs. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the antinociceptive effect of Asplenium nidus ethanolic extract (ANEE) using a Caenorhabditis elegans model. Methods: Sublethality assay was performed on ANEE to determine the experimental concentrations to be used for the antinociceptive assays. Antinociceptive effect of ANEE in C. elegans was investigated using mechanosensation assays in four treatment timepoints within 72 hours. Antinociceptive index (AI) was calculated for the cells treated with ANEE cells as well as morphine, paracetamol and control (!% DMSO). Results: The mechanosensation assays revealed that ANEE (104, 103, 102 µg/mL) had a significantly higher antinociceptive index (AI) (p<0.05) compared to the vehicle control (1% DMSO). The antinociceptive effects of ANEE, 2.5 µM morphine, and 0.01% mg/mL paracetamol in C. elegans were not significantly different (p>0.05). This effect of ANEE continued after four treatments within a 72-hour period. Conclusion: The findings revealed that A. nidus ethanolic extract (ANEE) possesses antinociceptive effect which validates folkloric use of A. nidus and suggest a potential for chronic therapeutic use. [ABSTRACT FROM AUTHOR]

Oral squamous cell carcinoma (OSCC) presents significant treatment challenges due to its poor survival and intense pain at the primary cancer site. Cancer pain is debilitating, contributes to diminished quality of life, and causes opioid tolerance. The stimulator of interferon genes (STING) agonism has been investigated as an anti-cancer strategy. We have developed STINGel, an extended-release formulation that prolongs the availability of STING agonists, which has demonstrated an enhanced anti-tumor effect in OSCC compared to STING agonist injection. This study investigates the impact of intra-tumoral STINGel on OSCC-induced pain using two separate OSCC models and nociceptive behavioral assays. Intra-tumoral STINGel significantly reduced mechanical allodynia in the orofacial cancer model and alleviated thermal and mechanical hyperalgesia in the hind paw model. To determine the cellular signaling cascade contributing to the antinociceptive effect, we performed an in-depth analysis of immune cell populations via single-cell RNA-seq. We demonstrated an increase in M1-like macrophages and N1-like neutrophils after STINGel treatment. The identified regulatory pathways controlled immune response activation, myeloid cell differentiation, and cytoplasmic translation. Functional pathway analysis demonstrated the suppression of translation at neuron synapses and the negative regulation of neuron projection development in M2-like macrophages after STINGel treatment. Importantly, STINGel treatment upregulated TGF-β pathway signaling between various cell populations and peripheral nervous system (PNS) macrophages and enhanced TGF-β signaling within the PNS itself. Overall, this study sheds light on the mechanisms underlying STINGel-mediated antinociception and anti-tumorigenic impact.

Tongkat ali (Eurycoma longifolia Jack) (ELJ) is a plant in the Simaroubaceae family. Its roots are used in traditional Thai medicine to treat inflammation, pain, and fever; however, the antiulcer abilities of its ethanolic extract have not been studied. This study examined the anti-inflammatory, antinociceptive, antipyretic, and gastroprotective effects of ethanolic ELJ extract in animal models and found that ELJ effectively reduced EPP-induced ear edema in a dose-dependent manner and that a high dose of ELJ inhibited carrageenan-induced hind paw edema formation. In cotton-pellet-induced granuloma formation, a high dose of ELJ suppressed the increases in wet granuloma weight but not dry or transudative weight. In the formalin-induced nociception study, ELJ had a significant dose-dependent inhibitory impact. Additionally, the study found that yeast-induced hyperthermia could be significantly reduced by antipyretic action at the highest dose of ELJ. In all the gastric ulcer models induced by chemical substances or physical activity, ELJ extracts at 150, 300, and 600 mg/kg also effectively prevented gastric ulcer formation. In the pyloric ligation model, however, the effects of ELJ extract on gastric volume, gastric pH, and total acidity were statistically insignificant. These findings support the current widespread use of Eurycoma longifolia Jack in traditional medicine, suggest the plant's medicinal potential for development of phytomedicines with anti-inflammatory, antinociceptive, and antipyretic properties, and support its use in the treatment of gastric ulcers due to its gastroprotective properties. [ABSTRACT FROM AUTHOR]

Salvia semiatrata Zucc. (Lamiaceae) is endemic to Oaxaca, Mexico, and is known for its analgesic properties. Terpenoids and phenolic compounds with antinociceptive potential have been characterised from this species. The aim of this research was to determine the variation in terpenoids and flavonoids in ethyl acetate extracts of S. semiatrata collected from ten different localities, as well as to evaluate the antinociceptive effect between plants with higher and lower contents of these secondary metabolites. Quantification of S. semiatrata compounds was performed via HPLC-DAD, whereas in vivo evaluation of the antinociceptive effect was performed via formalin test. The results showed that the most abundant groups of metabolites are oleanolic acid (89.60–59.20 µg/mg), quercetin (34.81–16.28 µg/mg), catechin (11.30–9.30 µg/mg), and 7-keto-neoclerodan-3,13-dien-18,19:15,16-diolide (7-keto) (8.01–4.76 µg/mg). Principal component and canonical correspondence analysis showed that the most contrasting localities in terms of compound content and climatic variables are Miahuatlán and Santiago Huauclilla. The differences in metabolite content between the two locations did not affect the antinociceptive effects evaluated at a dose of 300 mg/kg, p.o. In conclusion, the results indicate that S. semiatrata is effective in relieving pain, regardless of the site of collection, reinforcing its traditional use as analgesic. [ABSTRACT FROM AUTHOR]

Abstract Caesalpinia eriostachys Benth. (CE) is native to the Mexico and multiple effects have been observed from several plants belonging to the same family. CE was subjected to extraction with 95% ethanol, and the components were isolated through column chromatography. The structure of the compound was elucidated based on nuclear magnetic resonance (NMR) spectral data, electron ionization–mass (EI‐MS) spectroscopy, and liquid chromatography–mass (LC‐MS) spectroscopy. In vivo antinociceptive studies were conducted using writhing, 5% formalin, tail‐flick, hot‐plate, and von Frey filament tests. The ethanolic extract showed a significant effect in the acetic acid‐induced pain model and nociceptive behavior in the formalin model (second phase). In hot‐plate test and tail‐flick test, the results showed no difference compared to the control group. The results suggest that the ethanolic extract may act peripherally to reduce pain. In the streptozotocin (STZ)‐induced pain model, the ethanolic extract showed significant effect in the von Frey test model. The n‐Hex (Hexane) and MC (Methylene chloride) fractions and isolated compounds, ellagic acid and agathisflavone, showed increased effect. Based on these results, we confirmed that the CE ethanolic extract and their compounds, ellagic acid and agathisflavone, have antinociceptive effect on diabetes mellitus‐induced pain. Furthermore, the results of this study might be valuable for identifying compounds with antinociceptive activity from natural products.

Neuropathic pain is refractory to opioid analgesics. Since there are functional linkages between μ-opioid receptors (MOR) and cannabinoid receptors (CBR), the present study was designed to investigate the interactions between MOR and CB1R based on antinociceptive effects for neuropathic pain mediated through G protein-coupled inwardly-rectifying potassium channels (GIRKs). The antinociceptive effects against pseudonociceptive response or neuropathic pain of MOR and CBR agonists were assessed in mice with or without partial sciatic nerve ligation. To investigate the functional interaction between MOR and CB1R, electrophysiological recording through GIRK was performed using the two-electrode voltage-clamp method in oocytes along with Western blotting in the spinal cord of mice. Co-administration of the MOR agonist DAMGO and the CB1R agonist CP55,940 augmented inwardly rectifying K+ currents in Xenopus oocytes co-expressing MOR, CB1R and GIRK1/2. Further, combination of morphine and the CBR agonist WIN-55,212-2 produced prominent antinociceptive effects in an i.t. GIRK1 inhibitor-reversible manner. Furthermore, CB1R was upregulated under neuropathic pain in the spinal cord, and such upregulation and antinociceptive effects were not altered by repeated treatment with morphine plus WIN-55,212-2. Our findings suggest that co-administration of MOR and CBR agonists could enhance their antinociceptive effects through GIRK1 in the spinal cord of mice.

4-Arylhydrazinylidene-5-(polyfluoroalkyl)pyrazol-3-ones (4-AHPs) were found to be obtained by the regiospecific cyclization of 2-arylhydrazinylidene-3-(polyfluoroalkyl)-3-oxoesters with hydrazines, by the azo coupling of 4-nonsubstituted pyrazol-5-oles with aryldiazonium chlorides or by the firstly discovered acid-promoted self-condensation of 2-arylhydrazinylidene-3-oxoesters. All the 4-AHPs had an acceptable ADME profile. Varying the substituents in 4-AHPs promoted the switching or combining of their biological activity. The polyfluoroalkyl residue in 4-AHPs led to the appearance of an anticarboxylesterase action in the micromolar range. An NH-fragment and/or methyl group instead of the polyfluoroalkyl one in the 4-AHPs promoted antioxidant properties in the ABTS, FRAP and ORAC tests, as well as anti-cancer activity against HeLa that was at the Doxorubicin level coupled with lower cytotoxicity against normal human fibroblasts. Some Ph-N-substituted 4-AHPs could inhibit the growth of N. gonorrhoeae bacteria at MIC 0.9 μg/mL. The possibility of using 4-AHPs for cell visualization was shown. Most of the 4-AHPs exhibited a pronounced analgesic effect in a hot plate test in vivo at and above the diclofenac and metamizole levels except for the ones with two chlorine atoms in the aryl group. The methylsulfonyl residue was proved to raise the anti-inflammatory effect also. A mechanism of the antinociceptive action of the 4-AHPs through blocking the TRPV1 receptor was proposed and confirmed using in vitro experiment and molecular docking. [ABSTRACT FROM AUTHOR]

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Research background. Extracts from grape pomace, including the wine, show many biological effects such as antioxidant and anti-inflammatory activities. Unfortunately, winemakers discard the bagasse, so the waste is not exploited, although it contains bioactive compounds with antioxidant and anti-inflammatory properties. The work aims to analyze the hydroethanolic extract of peels from Vitis labrusca agro-industrial waste and to evaluate its antinociceptive and anti-inflammatory properties. This study is relevant for reusing a residue and adding value to the grape economic chain. Experimental approach. A representative sample of pomace was obtained and the peels were used to produce the extract. The phenolic compounds were determined by mass spectrometry in multiple reaction monitoring mode and Folin-Ciocalteu colorimetric method, using gallic acid as standard. The biological analyses were carried out using mice orally treated with crude extract at doses of 30, 100 and 300 mg/kg. We evaluated mechanical hyperalgesia by the von Frey method, thermal heat hyperalgesia using a hot plate at 55 °C, paw edema using a pachymeter, and neutrophil recruitment by measurement of myeloperoxidase activity. The nephrotoxicity and hepatotoxicity were evaluated by biochemical analyses using blood samples that were collected after the Vitis labrusca administration. Results and conclusions. In all wet winemaking residues peel mass fraction was 75%, and in dry residues 59%. We identified nine anthocyanins (3-O-glucosides: peonidin, delphinidin, petunidin and malvidin; 3-p-coumaroyl-glucosides: cyanidin, peonidin, petunidin and malvidin, and malvidin-3,5-diglucoside), five flavonoids (apigenin-7-glucoside, luteolin-7-glucoside, quercetin-3-galactoside, isorhamnetin-3-glucoside and myricetin-3-rutinoside), and mass fraction of phenolic compounds, expressed as gallic acid equivalents, was 26.62 mg/g. In vivo assays showed that Vitis labrusca extract at mass fractions 100 and 300 mg/kg reduced carrageenan-induced mechanical and thermal hyperalgesia, 50% of the paw edema, and neutrophil recruitment. In addition, there were no indications of nephrotoxicity and hepatotoxicity. Our extract obtained from winemaking residue has analgesic and anti-inflammatory properties, related at least in part to the presence of phenolic compounds, and it is not toxic to renal and hepatic tissues. Novelty and scientific contribution. This bio-product can be used as an alternative to synthetic anti-inflammatory agents with the same pharmacological potential and fewer side effects. We demonstrated that Vitis labrusca winemaking waste can be used for the production of antinociceptive and anti-inflammatory products (nutraceutical, pharmaceutical and cosmetics) without toxicity, contributing to the environmental economy.

This study aimed to assess the antinociceptive activity of extracts and fractions of Paeonia daurica subsp. macrophylla in BALB/c mice. Various doses of hydro-alcoholic extract (HE), hexane fraction (F-hexane), methanol (F-MeOH), and chloroform (F-CHCl3), as well as aqueous extracts (AE), were evaluated by a well-known model, a formalin-induced pain test in mice. All extracts, piroxicam 0.1 mg/kg, and negative control groups were administered 30 minutes before formalin injection. Flinching, licking, and biting reflexes were measured as painful factors compared with controls at intervals of 0 to 5 minutes, 0 to 15, and 0 to 60 minutes after formalin injection. The acute oral toxicity test of total ethanolic and aqueous extracts showed no signs of toxic effect up to a dose of 5000 mg/kg. In the formalin test at a time interval of 0 to 5 minutes, there was no significant difference between the results of the study groups. In the range of 0 to 15 minutes, the effect of AE (1 g/kg), HE (2, 3 g/kg), and F-hexane (1 g/kg) was significantly higher than the positive control group (p

To evaluate the antinociceptive effect and the possible mechanism of action of two polar extracts of Mansoa alliacea, a medicinal plant used in Perú, Brazil, and Mexico to treat rheumatic pain, we used the formalin and hot-plate tests in mice. We found that ethanolic (MA-EtOH) and aqueous (MA-AQ) extracts of M. alliacea induced antinociceptive effects in both nociceptive tests. The antinociceptive efficacy of the highest dosage (300 mg/kg) of both extracts were also compared by using intraperitoneal and oral administration in the formalin test. Results showed that intraperitoneal injection of the two extracts produced better antinociceptive effects than that obtained by their oral administration. The mechanism of action involved in their antinociceptive activity was determined in the formalin test. Results showed that the presence of A784168 (TRPV1 antagonist) did not alter the antinociceptive effect induced by any of the M. alliacea extracts, whereas naltrexone (opioid antagonist) partially prevented the antinociceptive effect only of MA-EtOH in both phases of the formalin test. Furthermore, the effects of the extracts were diminished by L-NAME (inhibitor of nitric oxide synthase), but not by ODQ (inhibitor of the soluble guanylyl cyclase) or glibenclamide (blocker of K+ATP channels) in the neurogenic phase. However, the effect of MA-AQ was diminished by all the inhibitors in the inflammatory phase. These results support the use of M. alliacea as a potential natural product with efficacy for pain relief depending on the form of preparation and the route of administration by involving opioid receptors and the production of nitric oxide.

Salvia semiatrata Zucc. (Lamiaceae) is endemic to Oaxaca, Mexico, and is known for its analgesic properties. Terpenoids and phenolic compounds with antinociceptive potential have been characterised from this species. The aim of this research was to determine the variation in terpenoids and flavonoids in ethyl acetate extracts of S. semiatrata collected from ten different localities, as well as to evaluate the antinociceptive effect between plants with higher and lower contents of these secondary metabolites. Quantification of S. semiatrata compounds was performed via HPLC-DAD, whereas in vivo evaluation of the antinociceptive effect was performed via formalin test. The results showed that the most abundant groups of metabolites are oleanolic acid (89.60–59.20 µg/mg), quercetin (34.81–16.28 µg/mg), catechin (11.30–9.30 µg/mg), and 7-keto-neoclerodan-3,13-dien-18,19:15,16-diolide (7-keto) (8.01–4.76 µg/mg). Principal component and canonical correspondence analysis showed that the most contrasting localities in terms of compound content and climatic variables are Miahuatlán and Santiago Huauclilla. The differences in metabolite content between the two locations did not affect the antinociceptive effects evaluated at a dose of 300 mg/kg, p.o. In conclusion, the results indicate that S. semiatrata is effective in relieving pain, regardless of the site of collection, reinforcing its traditional use as analgesic.

Tongkat ali (Eurycoma longifolia Jack) (ELJ) is a plant in the Simaroubaceae family. Its roots are used in traditional Thai medicine to treat inflammation, pain, and fever; however, the antiulcer abilities of its ethanolic extract have not been studied. This study examined the anti-inflammatory, antinociceptive, antipyretic, and gastroprotective effects of ethanolic ELJ extract in animal models and found that ELJ effectively reduced EPP-induced ear edema in a dose-dependent manner and that a high dose of ELJ inhibited carrageenan-induced hind paw edema formation. In cotton-pellet-induced granuloma formation, a high dose of ELJ suppressed the increases in wet granuloma weight but not dry or transudative weight. In the formalin-induced nociception study, ELJ had a significant dose-dependent inhibitory impact. Additionally, the study found that yeast-induced hyperthermia could be significantly reduced by antipyretic action at the highest dose of ELJ. In all the gastric ulcer models induced by chemical substances or physical activity, ELJ extracts at 150, 300, and 600 mg/kg also effectively prevented gastric ulcer formation. In the pyloric ligation model, however, the effects of ELJ extract on gastric volume, gastric pH, and total acidity were statistically insignificant. These findings support the current widespread use of Eurycoma longifolia Jack in traditional medicine, suggest the plant’s medicinal potential for development of phytomedicines with anti-inflammatory, antinociceptive, and antipyretic properties, and support its use in the treatment of gastric ulcers due to its gastroprotective properties.

Caesalpinia eriostachys Benth. (CE) is native to the Mexico and multiple effects have been observed from several plants belonging to the same family. CE was subjected to extraction with 95% ethanol, and the components were isolated through column chromatography. The structure of the compound was elucidated based on nuclear magnetic resonance (NMR) spectral data, electron ionization–mass (EI‐MS) spectroscopy, and liquid chromatography–mass (LC‐MS) spectroscopy. In vivo antinociceptive studies were conducted using writhing, 5% formalin, tail‐flick, hot‐plate, and von Frey filament tests. The ethanolic extract showed a significant effect in the acetic acid‐induced pain model and nociceptive behavior in the formalin model (second phase). In hot‐plate test and tail‐flick test, the results showed no difference compared to the control group. The results suggest that the ethanolic extract may act peripherally to reduce pain. In the streptozotocin (STZ)‐induced pain model, the ethanolic extract showed significant effect in the von Frey test model. The n‐Hex (Hexane) and MC (Methylene chloride) fractions and isolated compounds, ellagic acid and agathisflavone, showed increased effect. Based on these results, we confirmed that the CE ethanolic extract and their compounds, ellagic acid and agathisflavone, have antinociceptive effect on diabetes mellitus‐induced pain. Furthermore, the results of this study might be valuable for identifying compounds with antinociceptive activity from natural products. [ABSTRACT FROM AUTHOR]

Research background. Extracts from grape pomace, including the wine, show many biological effects such as antioxidant and anti-inflammatory activities. Unfortunately, winemakers discard the bagasse, so the waste is not exploited, although it contains bioactive compounds with antioxidant and anti-inflammatory properties. The work aims to analyze the hydroethanolic extract of peels from Vitis labrusca agro-industrial waste and to evaluate its antinociceptive and anti-inflammatory properties. This study is relevant for reusing a residue and adding value to the grape economic chain. Experimental approach. A representative sample of pomace was obtained and the peels were used to produce the extract. The phenolic compounds were determined by mass spectrometry in multiple reaction monitoring mode and Folin-Ciocalteu colorimetric method, using gallic acid as standard. The biological analyses were carried out using mice orally treated with crude extract at doses of 30, 100 and 300 mg/kg. We evaluated mechanical hyperalgesia by the von Frey method, thermal heat hyperalgesia using a hot plate at 55 °C, paw edema using a Vernier caliper, and neutrophil recruitment by measurement of myeloperoxidase activity. The nephrotoxicity and hepatotoxicity were evaluated by biochemical analyses using blood samples that were collected after the Vitis labrusca administration. Results and conclusions. In all wet winemaking residues peel mass fraction was 75 %, and in dry residues 59 %. We identified nine anthocyanins (3-O-glucosides: peonidin, delphinidin, petunidin and malvidin; 3-p-coumaroyl-glucosides: cyanidin, peonidin, petunidin and malvidin, and malvidin-3,5-diglucoside), five flavonoids (apigenin-7-glucoside, luteolin-7-glucoside, quercetin-3-galactoside, isorhamnetin-3-glucoside and myricetin-3-rutinoside), and mass fraction of phenolic compounds, expressed as gallic acid equivalents, was 26.62 mg/g. In vivo assays showed that Vitis labrusca extract at mass fractions 100 and 300 mg/kg reduced carrageenan-induced mechanical and thermal hyperalgesia, 50 % of the paw edema, and neutrophil recruitment. In addition, there were no indications of nephrotoxicity and hepatotoxicity. Our extract obtained from winemaking residue has analgesic and anti-inflammatory properties, related at least in part to the presence of phenolic compounds, and it is not toxic to renal and hepatic tissues. Novelty and scientific contribution. This bio-product can be used as an alternative to synthetic anti-inflammatory agents with the same pharmacological potential and fewer side effects. We demonstrated that Vitis labrusca winemaking waste can be used for the production of antinociceptive and anti-inflammatory products (nutraceutical, pharmaceutical and cosmetics) without toxicity, contributing to the environmental economy. [ABSTRACT FROM AUTHOR]

Preliminary pharmacological studies revealed that the EtOAc fraction (BGEA) might be the main active fraction with anti-inflammatory and antinociceptive effects in Beaumontia grandiflora Wall. Further assays on BGEA at doses of 200, 400, and 800 mg/kg using four animal models showed that it could inhibit the xylene-induced ear edema, carrageenan-induced paw edema, and acetic acid-induced writhing and prolong the latency time in the hot-plate test. ELISA analysis revealed that the anti-inflammatory activity of BGEA might be associated with the decrease of TNF- α , IL-1 β , and IL-6 levels and the increase of the IL-10 level. The acute toxicity test showed that except for the n -BuOH fraction, the LD 50 values of the extract and other three fractions were higher than 2000 mg/kg bw. Finally, 14 compounds were identified from BGEA by LC-MS. This research provides some basis for the folk use of B. grandiflora in the treatment of inflammation and pain-related diseases.

Objective: To analyse the antinociceptive interaction between quercetin (QUER) and diclofenac (DIC) in experimental arthritic gout-pain. Methods: The antinociceptive effect of DIC and QUER alone and in combination were evaluated using an arthritic gout-pain model. Pain was induced through intra-articular administration of uric acid in the rats and the treatments were administered 2 h later. Additionally, the cyclooxygenase (COX) activity was determined in rats treated with DIC, QUER and their combination. Key findings: DIC induced a maximal effect of 69.7 ± 2.7% with 3.1 mg/kg; whereas QUER only produced 17.6 ± 2.6% with the maximal dose (316 mg/kg). Ten of twelve DIC + QUER combinations showed a lesser antinociceptive effect than DIC alone did (P < 0.05). Moreover, DIC reduced total-COX (70.4 ± 1.3 versus 52.4 ± 1.8 and 77.4 ± 9.0 versus 56.1 ± 1.3, P < 0.05) and COX-2 (60.1 ± 1.0 versus 42.4 ± 1.8 and 58.1 ± 2.4 versus 48.7 ± 1.3, P < 0.05) activity after 1 and 3 h, respectively. Nevertheless, only the COX-2 activity induced by DIC was prevented in the presence of QUER (63.2 ± 3.0 versus 60.1 ± 1.0 and 56.6 ± 1.3 versus 58.1 ± 2.4 at 1 and 3 h, respectively). Conclusions: All these data demonstrated that the simultaneous administration of QUER + DIC produces an unfavorable interaction on the antinociceptive effect of DIC. Therefore, this combination might not be recommendable to relieve arthritic gout-pain. [ABSTRACT FROM AUTHOR]

To elucidate the antinociceptive, physiologic and biochemical effects of electroacupuncture (EA) and xylazine in hybrid goats. Prospective experimental study. A total of 30 female hybrid goats aged 1–2 years and weighing 25 ± 2.9 kg (mean ± standard deviation). The goats were divided into five groups and administered xylazine (0.1 mg kg−1; group XYL.1), xylazine (0.3 mg kg−1; group XYL.3), EA (group EA), EA + xylazine (0.1 mg kg−1; group XYL.1-EA) and 0.9% saline (0.3 mL; control group CON). Nociceptive threshold and serum glucose concentration were measured at time 0 and at 15, 30, 45, 60 minutes and 24 hours after treatment. Nociceptive threshold was measured by passing potassium ions through the skin using potassium iontophoresis. Mean arterial pressure (MAP), heart rate (HR), respiratory frequency (f R) and rectal temperature (RT) were recorded at times 0 and at 5, 10, 15, 20, 30, 45, 60 minutes and 24 hours. Repeated-measures analyses were performed for each response variable; p < 0.05 was considered significant for all analyses. Antinociceptive effects in groups XYL.1 and XYL.3 were increased significantly at 15–60 minutes compared with group CON. Antinociceptive effect was higher in group XYL.1-EA than groups XYL.1 or EA at 15–60 minutes (p < 0.05). No significant difference in the nociceptive threshold was recorded in groups XYL.1-EA and XYL.3, except at 30 minutes. HR, MAP, f R , RT values were higher in group XYL.1-EA than in groups XYL.1 or XYL.3. Serum glucose concentration was higher in group XYL.3 at 15–60 minutes than in CON. The XYL.1 and EA combination was effective for antinociception with minimum physiologic alteration, suggesting that the combination may be a new and effective strategy for pain relief during clinical procedures in goats. [ABSTRACT FROM AUTHOR]

Background:Ranolazine and trimetazidine are piperazine derivatives used in antianginal therapy. There are data on the use of these drugs in the treatment of neuropathic pain. In this study, it was aimed to evaluate the antinociceptive effects of ranolazine and trimetazidine.Methods: Sixty patients who were started on trimetazidine or ranolazine treatment were included in the study. The patients were evaluated with Seattle Angina Questionnaire (SAQ), Visual Analog Scale (VAS) and State-Trait Anxiety Inventory (STAI) on the first day of treatment and at the first month follow-up.Results: The SAQ scores of the patients given ranolazine were statistically significantly higher than the patients given trimetazidine. The most significant increase was observed in terms of treatment satisfaction (53.03 ± 8.11 vs. 72.88 ± 5.29, p < 0.001) and quality of life (49.79 ± 8.62 vs. 68.01 ± 0.65, p = 0.016). The decrease in VAS (p = 0.001) and the decrease in STAI scores (p = 0.002) after treatment in the ranolazine group were significantly higher than in the trimetazidine group.Conclusions: Ranolazine and trimetazidine are two effective drugs in antianginal treatment. While both drugs are effective on general systemic musculoskeletal pain and anxiety, the efficacy of ranolazine is more pronounced. [ABSTRACT FROM AUTHOR]

Berberine was identified in extracts of Berberis ruscifolia Lam., a plant used in traditional medicine as an analgesic. Its presence may be involved in the reported pharmacological activity of this species. However, there is still a lack of scientific research concerning its analgesic activity in the peripheral nervous system. To investigate Berb-induced antinociception in the formalin test and to evaluate several pathways related to its pharmacological antinociceptive effects in chemical models of nociception in mice. The antinociceptive activity of Berb was assessed by inducing the paw licking in mice with different allodynic agents. In the formalin test, the antiedematous and antithermal effect of Berb was evaluated simultaneously in the same experiment. Other nociceptive behavior produced by endogenous [prostaglandin E 2 (PGE 2), histamine (His), glutamate (Glu) or bradykinin (BK)] or exogenous [capsaicin (Caps) and cinnamaldehyde (Cin)] chemical stimuli, and activators as protein kinase A (PKA) and C (PKC), were also evaluated.The in vivo doses for p.o. were 3 and 30 mg/kg. Berb, at 30 mg/kg p.o., showed a significant inhibition of the nociceptive action in formalin in both phases being stronger at the inflammatory phase (59 ± 9%) and more active than Asp (positive control) considering the doses evaluated. Moreover, Berb inhibited the edema (34 ± 10%), but not the temperature in the formalin test. Regarding the different nociceptive signaling pathways evaluated, the most relevant data were that the administration of p.o. of Berb, at 30 mg/kg, caused significant inhibition of nociception induced by endogenous [His (72 ± 11%), PGE 2 (78 ± 4%), and BK (51 ± 7%)], exogenous [Cap (68 ± 4%) and Cinn (57 ± 5%)] compounds, and activators of the PKA [(FSK (86 ± 3%)] and PKC [(PMA(86 ± 6%)] signaling pathway. Berb did not inhibit the nociceptive effect produced by Glu. The present study demonstrated, for the first time, the potential of Berb in several nociceptive tests, with the compound present in B. ruscifolia contributing to the analgesic effect reported for this species. [Display omitted] • Berberine shows antinociceptive effects at the peripheral level in mouse pain models. • Different allogeneic agents evaluated demonstrated antinociceptive effects of Berberine. • Berberine showed an analgesic effect, in part by inhibiting PKC and PKA activation. • Berberine collaborates with the analgesic effect proclaimed in B. ruscifolia extracts. [ABSTRACT FROM AUTHOR]

Context: The search of new substances with analgesic properties has grown in the last years. Brazil and Cuba have a big biodiversity allowing the study of several plants with potential pharmacological activities. Aims: To evaluate the chemical composition and potential antinociceptive effect of the ethanolic extract from Clusia minor L. leaves (Clusiaceae) in mice. Methods: Phytochemical characterization was performed by Gas Chromatography/Mass Spectrometry. Antinociceptive effect was evaluated using acetic acid, formalin, hot plate, and capsaicin models. Mechanical hypernociception was induced by intraplantar carrageenan, tumor necrosis factor α (TNFα) and prostagladin E2 (PGE2) and responses were measured after 3 h of injection. Results: Mass Spectrometry analysis allowed the identification of 16 compounds. Fatty acid derivatives, steroids, triterpenoids, and vitamin E were the main findings. The most abundant sterol was β-sitosterol (14.04%); followed by the triterpenes α-amyrin (11.94%), and β-amyrin (7.82%). Vitamin E represented the 8.44% of the total identified compounds. The evaluation of the acetic acid-induced nociception model showed that the extract was effective in reducing pain in a dose-dependent manner. This resulted in a maximal inhibition of 53 ± 4%. The extract was also effective in other pain models. Additionally, the extract presented a considerable inhibition of paw mechanical hypernociception. Conclusions: The data suggest that the antinociceptive effect of Clusia minor occurs by interaction of various mechanisms; which probably take places via central and peripheral pathway. Therefore, modulating the inflammatory and neurogenic pain.

Our previous research has shown that galanin plays an antinociceptive effect via binding to galanin receptors (GalRs) in nucleus accumbens (NAc). This study focused on the involvement of GalR2 in galanin-induced antinociceptive effect in NAc of neuropathic pain rats. The chronic constriction injury of sciatic nerve (CCI) was used to mimic neuropathic pain model. The hind paw withdrawal latency (HWL) to thermal stimulation and hind paw withdrawal threshold (HWT) to mechanical stimulation were measured as the indicators of pain threshold. The results showed that 14 and 28 days after CCI, the expression of GalR2 was up-regulated in bilateral NAc of rats, and intra-NAc injection of GalR2 antagonist M871 reversed galanin-induced increases in HWL and HWT of CCI rats. Furthermore, intra-NAc injection of GalR2 agonist M1145 induced increases in HWL and HWT at day 14 and day 28 after CCI, which could also be reversed by M871. Finally, we found that M1145-induced antinociceptive effect in NAc of CCI rats was stronger than that in intact rats. These results imply that the GalR2 is activated in the NAc from day 14 to day 28 after CCI and GalR2 is involved in the galanin-induced antinociceptive effect in NAc of CCI rats. [ABSTRACT FROM AUTHOR]

Objectives: Safe and effective drugs are still lacking for many pain therapies. In recent years, growing interest has been devoted thus on herbal drugs as an option to identify new pain killers. Based on this, extensive researches are carried out on Verbascum L. genus due to its therapeutic potency on pain and inflammation therapy. In this study, among Verbascum species, the antinociceptive effect of Verbascum exuberans Hub.-Mor., and its contributions to nitrergic, serotonergic, or opioidergic pathways as well as its antiinflammatory acitivity were investigated. Materials and Methods: Tail clip, tail flick, and hot plate tests were used to determine the central (spinal and supraspinal) antinociceptive effect, while an acetic acid-induced writhing test was used to measure the peripheral antinociceptive effect of the extract (250 and 500 mg/kg). The extract (250 mg/kg) was then combined with nω-nitro-L-arginine methyl ester, cyproheptadine, and naloxone to evaluate its involvement in nitrergic, serotonergic, or opioidergic pathways, respectively. Carrageenan-induced hind paw edema model was used to determine the antiinflammatory effect of the extract (250 mg/kg). Results: The extract shows central spinal but not central supraspinal antinociceptive effect, and presents peripheral antinociceptive effect. The antinociceptive actions of the extract is largely regulated via targeting the nitrergic pathway, while the opioidergic pathway is partly involved. Further, the extract shows antiinflammatory effect due to the significant inhibitions on the time dependent edema progression and the cytokine (tumor necrosis factor-alfa and interleukin-1beta) productions. [ABSTRACT FROM AUTHOR]

The present paper focuses on the synthesis and characterization of new hydrogels and drug delivery systems, designed for local therapy. The hydrogels were obtained by reacting PEG-ylated chitosan derivatives with citral in different molar ratios of their functionalities. The drug delivery systems were obtained by the in situ hydrogelation of PEG-ylated chitosan derivatives with citral, in the presence of a hydrophilic anti-inflammatory drug, diclofenac sodium salt. The hydrogels and the drug delivery systems were characterized from the structural, supramolecular and morphological points of view by FTIR spectroscopy, wide angle X-ray diffraction, polarized optical microscopy and scanning electron microscopy. The in vitro release kinetics of the drug has been monitored in physiological conditions, while the in vivo release was evaluated by the somatic pain model on rats. The in vitro enzymatic degradability of the hydrogels was evaluated in the presence of lysozyme, leading to a significant mass loss of 47% in 21 days. All the findings, recommend the investigated materials as promising candidates for local drug delivery applications. Unlabelled Image [ABSTRACT FROM AUTHOR]

Chronic neuropathic pain poses a significant health problem, for which effective therapy is lacking. The current work aimed to investigate the potential antinociceptive efficacy of isorhynchophylline, an oxindole alkaloid, against neuropathic pain and elucidate mechanisms. Male C57BL/6J mice were subjected to chronic constriction injury (CCI) by loose ligation of their sciatic nerves. Following CCI surgery, the neuropathic mice developed pain-like behaviors, as shown by thermal hyperalgesia in the Hargreaves test and tactile allodynia in the von Frey test. Repetitive treatment of CCI mice with isorhynchophylline (p.o., twice per day for two weeks) ameliorated behavioral hyperalgesia and allodynia in a dose-dependent fashion (5, 15, and 45 mg/kg). The isorhynchophylline-triggered antinociception seems serotonergically dependent, since its antinociceptive actions on neuropathic hyperalgesia and allodynia were totally abolished by chemical depletion of spinal serotonin by PCPA, whereas potentiated by 5-HTP (a precursor of 5-HT). Consistently, isorhynchophylline-treated neuropathic mice showed escalated levels of spinal monoamines especially 5-HT, with depressed monoamine oxidase activity. Moreover, the isorhynchophylline-evoked antinociception was preferentially counteracted by co-administration of 5-HT1A receptor antagonist WAY-100635. In vitro, isorhynchophylline (0.1-10 nM) increased the Emax (stimulation of [35S] GTPγS binding) of 8-OH-DPAT, a 5-HT1A agonist. Of notable benefit, isorhynchophylline was able to correct co-morbidly behavioral symptoms of depression and anxiety evoked by neuropathic pain. Collectively, these findings confirm, for the first time, the disease-modifying efficacy of isorhynchophylline on neuropathic hypersensitivity, and this effect is dependent on spinal serotonergic system and 5-HT1A receptors.

This study offers a novel oral pregabalin (PG)-loaded drug delivery system based on chitosan and hypromellose phthalate-based polymeric nanocomposite in order to treat neuropathic pain (PG-PN). PG-PN has a particle size of 432 ± 20 nm, a polydispersity index of 0.238 ± 0.001, a zeta potential of +19.0 ± 0.9 mV, a pH of 5.7 ± 0.06, and a spherical shape. Thermal and infrared spectroscopy confirmed nanocomposite generation. PG-PN pharmacokinetics was studied after a single oral dose in male Wistar rats. PG-PN showed greater distribution and clearance than free PG. The antinociceptive effect of PG-PN in neuropathic pain rats was tested by using the chronic constriction injury model. The parameter investigated was the mechanical nociceptive threshold measured by the von Frey filaments test; PG-PN showed a longer antinociceptive effect than free PG. The rota-rod and barbiturate sleep induction procedures were used to determine adverse effects; the criteria included motor deficit and sedative effects. PG-PN and free PG had plenty of motors. PG-PN exhibited a less sedative effect than free PG. By prolonging the antinociceptive effect and decreasing the unfavorable effects, polymeric nanocomposites with pregabalin have shown promise in treating neuropathic pain.

Morphine is a strong painkiller acting through mu-opioid receptor (MOR). Full-length 7-transmembrane (TM) variants of MOR share similar amino acid sequences of TM domains in rodents and humans; however, interspecies differences in N- and C-terminal amino acid sequences of MOR splice variants dramatically affect the downstream signaling. Thus, it is essential to develop a mouse model that expresses human MOR splice variants for opioid pharmacological studies. We generated 2 lines of fully humanized MOR mice (hMOR; mMOR mice), line #1 and #2. The novel murine model having human OPRM1 genes and human-specific variants was examined by reverse-transcription polymerase chain reaction and the MinION nanopore sequencing. The differences in the regional distribution of MOR between wild-type and humanized MOR mice brains were detected by RNAscope and radioligand binding assay. hMOR; mMOR mice were characterized in vivo using a tail-flick, charcoal meal, open field, tail suspension, naloxone precipitation tests, and rectal temperature measurement. The data indicated that wild-type and humanized MOR mice exhibited different pharmacology of morphine, including antinociception, tolerance, sedation, and withdrawal syndromes, suggesting the presence of species difference between mouse and human MORs. Therefore, hMOR; mMOR mice could serve as a novel mouse model for pharmacogenetic studies of opioids. [ABSTRACT FROM AUTHOR]

Background: There is a wide range of animal models available today for studying chronic pain associated with a variety of etiologies and an extensive list of clinical manifestations of peripheral neuropathies. Photobiomodulation is a new tool for the treatment of pain in a convenient, noninvasive way. Objective: The aim of this work is to elucidate the effects of infrared light‐emitting diodes (LEDs) on behavioral responses to nociceptive stimuli in chronic pain models. Methods: Forty‐eight Swiss male mice weighing 25 to 35 g were used. Two chronic pain models, ischemia‐reperfusion (IR) and spared spinal nerve injury, were performed and then treated with infrared LED irradiation (390 mW, 890 nm, 17.3 mW/cm2, 20.8 J/cm2, for 20 minutes). The behavioral tests used were a mechanical hypersensitivity test von Frey test) and a cold allodynia test (acetone test). Results: The results showed that, in the IR model, the infrared LED had a significant effect on mechanical stimulation and cold allodynia on every day of treatment. In the spared nerve injury model, an analgesic effect was observed on every treatment day (when started on the 3rd and 7th days after the surgery). In both models, the effect was abolished when the treatment was interrupted. Conclusions: These findings suggest that photobiomodulation therapy may be a useful adjunct treatment for chronic pain. [ABSTRACT FROM AUTHOR]

Chronic neuropathic pain poses a significant health problem, for which effective therapy is lacking. The current work aimed to investigate the potential antinociceptive efficacy of isorhynchophylline, an oxindole alkaloid, against neuropathic pain and elucidate mechanisms. Male C57BL/6J mice were subjected to chronic constriction injury (CCI) by loose ligation of their sciatic nerves. Following CCI surgery, the neuropathic mice developed pain-like behaviors, as shown by thermal hyperalgesia in the Hargreaves test and tactile allodynia in the von Frey test. Repetitive treatment of CCI mice with isorhynchophylline (p.o., twice per day for two weeks) ameliorated behavioral hyperalgesia and allodynia in a dose-dependent fashion (5, 15, and 45 mg/kg). The isorhynchophylline-triggered antinociception seems serotonergically dependent, since its antinociceptive actions on neuropathic hyperalgesia and allodynia were totally abolished by chemical depletion of spinal serotonin by PCPA, whereas potentiated by 5-HTP (a precursor of 5-HT). Consistently, isorhynchophylline-treated neuropathic mice showed escalated levels of spinal monoamines especially 5-HT, with depressed monoamine oxidase activity. Moreover, the isorhynchophylline-evoked antinociception was preferentially counteracted by co-administration of 5-HT1A receptor antagonist WAY-100635. In vitro , isorhynchophylline (0.1-10 nM) increased the Emax (stimulation of [35S] GTPγS binding) of 8-OH-DPAT, a 5-HT1A agonist. Of notable benefit, isorhynchophylline was able to correct co-morbidly behavioral symptoms of depression and anxiety evoked by neuropathic pain. Collectively, these findings confirm, for the first time, the disease-modifying efficacy of isorhynchophylline on neuropathic hypersensitivity, and this effect is dependent on spinal serotonergic system and 5-HT1A receptors. [ABSTRACT FROM AUTHOR]

Abstract Background Bone cancer pain (BCP) severely compromises the quality of life, while current treatments are still unsatisfactory. Here, we tested the antinociceptive effects of triptolide (T10), a substance with considerable anti-tumor efficacies on BCP, and investigated the underlying mechanisms targeting the spinal dorsal horn (SDH). Methods Intratibial inoculation of Walker 256 mammary gland carcinoma cells was used to establish a BCP model in rats. T10 was intrathecally injected, and mechanical allodynia was tested by measuring the paw withdrawal thresholds (PWTs). In mechanism study, the activation of microglia, astrocytes, and the mitogen-activated protein kinase (MAPK) pathways in the SDH were evaluated by immunofluorescence staining or Western blot analysis of Iba-1, GFAP, p-ERK, p-p38, and p-JNK. The expression and cellular localization of histone deacetylases (HDACs) 1 and 2 were also detected to investigate molecular mechanism. Results Intrathecal injection of T10 inhibited the bone cancer-induced mechanical allodynia with an ED50 of 5.874 μg/kg. This effect was still observed 6 days after drug withdrawal. Bone cancer caused significantly increased expression of HDAC1 in spinal microglia and neurons, with HDAC2 markedly increased in spinal astrocytes, which were accompanied by the upregulation of MAPK pathways and the activation of microglia and astrocytes in the SDH. T10 reversed the increase of HDACs, especially those in glial cells, and inhibited the glial activation. Conclusions Our results suggest that the upregulation of HDACs contributes to the pathological activation of spinal glial cells and the chronic pain caused by bone cancer, while T10 help to relieve BCP possibly via inhibiting the upregulation of HDACs in the glial cells in the SDH and then blocking the neuroinflammation induced by glial activation.

Clinically, neuropathic pain treatment remains a challenging issue because the major therapy, centred around pharmacological intervention, is not satisfactory enough to patient by reason of low effectiveness and more adverse reaction. Therefore, it is still necessary to find more effective and safe therapy to ameliorate neuropathic pain. The purpose of this study was to explore the antinociceptive effect of Echinacoside (ECH), an active compound of Cistanche deserticola Ma, on peripheral neuropathic pain induced by chronic constriction injury (CCI) in mice, and to demonstrate its potential mechanism in vivo and vitro. In the present study, results showed that intraperitoneal administration of ECH (50, 100, and 200 mg/kg) could alleviate mechanical allodynia, cold allodynia and thermal hyperalgesia via behavioural test. Moreover, the structure and function of injured sciatic nerve by CCI were taken a turn for the better to a certain extent after ECH treatment using histopathological and electrophysiological test. Furthermore, ECH repressed the expression of the P2X7R and FKN and reduced the expression and release of the IL-1β, IL-6 and TNF-α. Besides, ECH could decrease Ca2+ influx and Cats efflux and inhibit phosphorylation of p38MAPK. To sum up, the present study illustrated that ECH could alleviate peripheral neuropathic pain by inhibiting microglia overactivation and inflammation through P2X7R/FKN/CX3CR1 signalling pathway in spinal cord. This study would provide a new perspective and strategy for the pharmacological treatment on neuropathic pain. [Display omitted] • Echinacoside ameliorated CCI-induced neuropathic pain in mice. • Echinacoside alleviated peripheral neuropathic pain through inhibiting P2X7R/FKN/CX3CR1 pathway in spinal cord. • Echinacoside may have potential as therapeutic agent for neuropathic pain. [ABSTRACT FROM AUTHOR]

The kappa opioid receptor (KOR) represents an attractive target for the development of drugs as potential antidepressants, anxiolytics and analgesics. A robust computational approach may guarantee a reduction in costs in the initial stages of drug discovery, novelty and accurate results. In this work, a virtual screening workflow of a library consisting of ~6 million molecules was set up, with the aim to find potential lead compounds that could manifest activity on the KOR. This in silico study provides a significant contribution in the identification of compounds capable of interacting with a specific molecular target. The main computational techniques adopted in this experimental work include: (i) virtual screening; (ii) drug design and leads optimization; (iii) molecular dynamics. The best hits are tripeptides prepared via solution phase peptide synthesis. These were tested in vivo, revealing a good antinociceptive effect after subcutaneous administration. However, further work is due to delineate their full pharmacological profile, in order to verify the features predicted by the in silico outcomes.

Background. The increase of NSAIDs safety is current direction of modern pharmacology, because of so-called "class-specific" adverse reactions, which are common to this class, and the leading place among them is occupied by gastro-intestinal toxicity. In previous studies we have proved the ability of vinboron to neutralize ulcerogenic effect of ibuprofen (Hladkykh F.V. and al., 2014). The presence of the proven analgesic activity in the domestic antispasmodics (Stepaniuk H.I. and al., 2007) serves as the basis for research of vinboron action on analgesic aspect of ibuprofen pharmacotherapeutic effec. Aim is to conduct research in silico of the relation «molecular structure – anelgetic activity» of vinboron and to prove experimentally in vivo the practicability of vinboron using with the aim to increase the analgesic activity of ibuprofen on the model of adjuvant arthritis in rats. Materials and methods. The study of the relation «molecular structure – activity anelgetic» of vinboron was conducted in silico by PASS- analysis of biological activity spectrum. The analysis was set online with direct insertion of structural formula of vinboron in browser using Marvin JS web-resource «PASS Online» (http://www.way2drug.com/passonline). Analgesic activity in vivo was studied on the model of acute thermal pain, which was simulated in the conventional behavioral test of nociception «Hot plate». The lag of pain reaction was determined at the beginning («0» day), on 7, 14, 21 and 28 days of experiment. Results and discussion. According to the PASS-forecast the mechanisms of vinboron analgesic activity is caused by agonism towards the vanilloid (TRPV1) receptors (Pa=0,490; Pi=0,008), agonism to the μ (mu) – receptor (Pa=0,323; Pi=0,036), inhibition of GABA (Pa=0,329; Pi=0,089) and others. Experimental studies have shown that the combined administration of ibuprofen and vinboron analgesic activity was higher than the results by ibuprofen monotherapy at a dose of 73 mg/kg up by 15.3%, and at a dose of 218 mg/kg up by 20.4%. Besides, it is worthwhile to note that analgesic activity during the integrated administration of ibuprofen at a dose of 218 mg/kg and vinboron (+39.8%) was higher than the total analgesic activity of ibuprofen monotherapy at the same dose (+19.4%) and monotherapy of vinboron (+10.9%), that points at potentiation of analgesic effect of both drugs during their integrated administration. Conclusions. According to the PASS-analysis, the leading mechanism in analgesic component implementation of vinboron is its agonism to TRPV1. The results of our in vivo studies point at the ability of vinboron to intensify the antinociceptive activity of ibuprofen.

Sigma-1 receptor (σ1R) antagonism increases the effects of morphine on acute nociceptive pain. S1RA (E-52862) is a selective σ1R antagonist widely used to study the role of σ1Rs. S1RA alone exerted antinociceptive effect in the formalin test in rats and increased noradrenaline levels in the spinal cord, thus accounting for its antinociceptive effect. Conversely, while systemic S1RA failed to elicit antinociceptive effect by itself in the tail-flick test in mice, it did potentiate the antinociceptive effect of opioids in this acute pain model. The present study aimed to investigate the site of action and the involvement of spinal noradrenaline on the potentiation of opioid antinociception by S1RA on acute thermal nociception using the tail-flick test in rats. Local administration was performed after intrathecal catheterization or intracerebroventricular and rostroventral medullar (RVM) cannulae implantation. Noradrenaline levels in the spinal cord were evaluated using the concentric microdialysis technique in awake, freely-moving rats. Systemic or supraspinal administration of S1RA alone, while having no effect on antinociception, enhanced the effect of morphine in rats. However, spinal S1RA administration did not potentiate the antinociceptive effect of morphine. Additionally, the peripherally restricted opioid agonist loperamide was devoid of antinociceptive effect but produced antinociception when combined with S1RA. Neurochemical studies revealed that noradrenaline levels in the dorsal horn of the spinal cord were not increased at doses exerting potentiation of the antinociceptive effect of the opioid. In conclusion, the site of action of σ1R for opioid modulation on acute thermal nociception is located at the peripheral and supraspinal levels, and the opioid-potentiating effect is independent of the spinal noradrenaline increase produced by S1RA.

Hemiphragma heterophyllum Wall. is commonly used in traditional Yi herbal medicine for treating bellyache and toothache. In the current study, an unreported monoterpene glucoside, ( S )-thymoquinol O -(6- O -oleuropeoyl)- β -d-glucopyranoside ( 1 ), together with 11 known glucosides were obtained from the whole herb of H. heterophyllum . Their structures were determined based on a detailed analysis of spectroscopic data and acid hydrolysis and methanolysis reactions. Bioassay results showed that compounds 1 and 10 at 40 mg/kg exhibited significant antinociceptive activity in the acetic acid-induced writhing model, with inhibitions of 59.80% and 64.07%, respectively. Moreover, five of the isolates showed moderate anti- α -glucosidase activities with IC 50 values ranging from 5.67 to 46.16 μM.

Background: The development of analgesic and anti-inflammatory drugs plays a crucial role in modern medicine, aiming to alleviate pain and reduce inflammation in patients. Opioids and nonsteroidal anti-inflammatory drugs are groups of drugs conventionally used to treat pain and inflammation, but a wide range of adverse effects and ineffectiveness in some pathological conditions leads us to search for new drugs with analgesic and anti-inflammatory properties., Objectives: In this regard, the authors intend to investigate the ((2s,6s)-6-ethyl-tetrahydro-2h-pyran- 2-yl) methanol compound (LS20) on pain and acute inflammation., Methods: Male Swiss mice were evaluated using acetic acid-induced abdominal writhing, formalin, and tail-flick as models of nociceptive evaluation and edema paw, air pouch and cell culture as models of inflammatory evaluation besides the rotarod test for assessment of motor impairment., Results: The compound showed an effect on the acetic acid-induced abdominal writhing, formalin and tail-flick tests. Studying the mechanism of action, reversion of the antinociceptive effect of the compound was observed from previous intraperitoneal administration of selective and non-selective opioid antagonists on the tail flick test. In addition, the compound induced an antiedematogenic effect and reduced leukocyte migration and the production of pro-inflammatory cytokines in the air pouch model. LS20 was able to maintain cell viability, in addition to reducing cell production of TNF-α and IL-6., Conclusion: In summary, the LS20 compound presented an antinociceptive effect, demonstrating the participation of the opioid system and an anti-inflammatory effect related to the inhibition of pro-inflammatory cytokine production. The compound also demonstrated safety at the cellular level., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: Opiorphin has been reported to show a stronger analgesic effect than morphine without causing side effects brought about by morphine-like drugs. Functional opiorphin analogs have been created to enhance its metabolic stability and preserve its potent analgesic effect., Objective: We conducted a systematic review to summarize all opiorphin analogs and identify those with the strongest metabolic stability and antinociceptive effect., Methods: From a total of 122 articles, 11 made it to the quantitative synthesis phase. The included articles were categorized into the type of modifications used to improve the metabolic stability of the peptide, metabolism and toxicity profile, drug absorption and in vitro cytotoxicity, anti-nociceptive effect, the opiorphin analogs' administration in animals or humans, and the type of the test used to test the antinociceptive effect., Results: The substitution of natural amino acid with a non-natural amino acid, side-chain modifications, or D-aminoacid substitution were the most used type of peptide modification to create opiorphin analogs. STR-324 and PEGylated liposomes loaded with opiorphin showed the best metabolism and toxicity performance. [C]-[(CH 2 ) 6 ]-QRF-[S-O-(CH 2 ) 8 ]-R showed high stability in human plasma and stronger inhibitory potency. YQRFSR and PEGylated liposomes loaded with opiorphin showed a stronger antinociceptive effect than the parent opiorphin or morphine, with an analgesic effect of PEGylated liposomes lasting more than 50%. Intravenous administration was the preferred method of opiorphin analog administration, and different tests were used to test the antinociceptive effect., Conclusion: This paper presents the first systematic review discussing opiorphin and opiorphin analogs and identifies the most promising candidates for future research., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Neuropathic pain is described as the “most terrible of all tortures that a nerve wound may inflict.” The aim of the present study was to demonstrate the antinociceptive effect of Symplocos chinensis f. pilosa Ohwi water extract (SCW) and synthesized derivatives of the isolated compound. The antinociceptive effect was tested using the acetic acid-induced writhing and 5% formalin tests. Antinociceptive effects on neuropathic pain were evaluated using the von Frey test with chronic constriction injury (CCI) and surgical nerve injury (SNI) models and tail-flick test with a vincristine-induced pain model. An Ames test was also conducted. 5-hydroxymethylfurfural (5-HMF) was isolated and derivatives were synthesized with various acid groups. Among the plant water extracts, SCW showed significantly effective activity. Additionally, SCW presented antinociceptive effects in the neuropathic pain models. The SCW water fraction resulted in fewer writhes than the other fractions, and isolated 5-HMF was identified as an effective compound. Because 5-HMF revealed a positive response in the Ames test, derivatives were synthesized. Among the synthesized derivations, 5-succinoxymethylfurfural (5-SMF) showed the best effect in the neuropathic pain model. Our data suggest that SCW and the synthesized compound, 5-SMF, possess effective antinociceptive activity against neuropathic pain.

Achillea biebersteinii is a perennial aromatic herb that grows in the Mediterranean area. The leaves of this plant are used in foods as bittering and appetizing agents. In folk medicine, it is used for the treatment of stomachache and abdominal pain. In this study, the analgesic effect of A. biebersteinii methanolic flower extract was tested in three pain models, namely: writhing, tail-flick and paw-licking (formalin) tests. A. biebersteinii extract inhibited abdominal cramps produced by acetic acid. The effect of A. biebersteinii was better than that of 70 mg/kg indomethacin. In tail flick, A. biebersteinii extract increased latency at 30 min and was as effective as 100 mg/kg diclofenac sodium. In formalin test, A. biebersteinii extracts decreased paw-licking and flinching response in early and late phases. Atropine blocked the action of A. biebersteinii extract (300 mg/kg) in the late phase of formalin test as well as in writhing and tail-flick tests. GC–MS analysis revealed that ascaridole and iso-ascaridole were the main constituents of A. biebersteinii flower extract. In conclusion, this study shows for the first time that the antinociceptive effect of A. biebersteinii is mediated by the cholinergic receptor. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the anti-nociceptive effect of gabapentin in acute and chronic pain models. Methods: Four mouse models of pain were used in this study. These comprised thermal tests (hot plate and tail immersion tests), and chemical tests (formalin and acetic acid-induced writhing tests). A total of seventy-two (72) albino mice weighing 25 - 40 g (mean weight = 32.5 ± 5.1 g) were used. In each test, the mice were randomly assigned to three sets of 6 mice each: control group, celecoxib group and drug treatment group. Each test was performed at intervals of 30, 60 and 90 min. Results: During the acute phase, there was no significant decrease in foot raising (FR) or licking and biting (L & B) episodes among the groups (p > 0.05). However, these episodes were significantly (p < 0.05) decreased in the second delayed phase, in the celecoxib and drug-treated groups, when compared with normal control group. Gabapentin significantly (p < 0.05) decreased pain response throughout the course of the thermal tests. The number of writhes within 30 min were significantly reduced in celecoxib and gabapentin-treated animals, compared with negative control group (p < 0.05). Gabapentin produced approximately 60 % protection of writhing, similar to that produced by celecoxib, the standard non-steroidal anti-inflammatory drug (NSAID) used (61 %). Conclusion: The results demonstrate that the gabapentin is effective against chronic inflammatory pain in mice and therefore can be potentially developed as an effective anti-inflammatory agent for humans. [ABSTRACT FROM AUTHOR]

• XPro1595 attenuates the mechanical allodynia of BCP in a dose-dependent manner. • XPro1595suppresses the tumor cell inoculation-induced activation of astrocytes and microglia in the SDH. • XPro1595 decreases the upregulation of pro-inflammatory cytokine expression in the SDH of BCP rats. • XPro1595 inhibits the phosphorylation of p38 but not ERK or JNK of MAPK signaling pathway in the SDH of BCP rats. Bone cancer pain (BCP) profoundly compromises the life quality of patients with bone metastases. Severe side effects of the drugs which were widely used and effective in the various stages of this condition results in a huge challenge for BCP treatment. Here, we investigated the antinociceptive effects of XPro1595, a soluble tumor necrosis factor (solTNF) inhibitor with considerable immunoregulatory efficacy, on BCP, as well as the underlying mechanisms within the spinal dorsal horn (SDH). Walker 256 mammary gland carcinoma cells were intratibially inoculated to induce BCP. Intrathecal administration of XPro1595 alleviated bone cancer-induced chronic pain in a dose-dependent manner, with an ED 50 of 9.69 mg/kg. Bone cancer resulted in the activation of astrocytes and microglia in the SDH through the upregulation of mitogen-activated protein kinase (MAPK) pathways, which was accompanied by an over-expression of pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-6. XPro1595suppressed bone cancer-evoked glial activation and the consequent neuroinflammation. These inhibitory effects of XPro1595 were, at least partially, mediated by a reduction in the phosphorylation of p38 MAPK in spinal glial cells. In conclusion, inhibition of spinal glia by XPro1595 may have utility in the treatment of bone cancer-induced neuroinflammation, and our results further implicate XPro1595 as a new promising therapeutic agent for BCP. [ABSTRACT FROM AUTHOR]

Sigma-1 receptor (σ1R) antagonism increases the effects of morphine on acute nociceptive pain. S1RA (E-52862) is a selective σ1R antagonist widely used to study the role of σ1Rs. S1RA alone exerted antinociceptive effect in the formalin test in rats and increased noradrenaline levels in the spinal cord, thus accounting for its antinociceptive effect. Conversely, while systemic S1RA failed to elicit antinociceptive effect by itself in the tail-flick test in mice, it did potentiate the antinociceptive effect of opioids in this acute pain model. The present study aimed to investigate the site of action and the involvement of spinal noradrenaline on the potentiation of opioid antinociception by S1RA on acute thermal nociception using the tail-flick test in rats. Local administration was performed after intrathecal catheterization or intracerebroventricular and rostroventral medullar (RVM) cannulae implantation. Noradrenaline levels in the spinal cord were evaluated using the concentric microdialysis technique in awake, freely-moving rats. Systemic or supraspinal administration of S1RA alone, while having no effect on antinociception, enhanced the effect of morphine in rats. However, spinal S1RA administration did not potentiate the antinociceptive effect of morphine. Additionally, the peripherally restricted opioid agonist loperamide was devoid of antinociceptive effect but produced antinociception when combined with S1RA. Neurochemical studies revealed that noradrenaline levels in the dorsal horn of the spinal cord were not increased at doses exerting potentiation of the antinociceptive effect of the opioid. In conclusion, the site of action of σ1R for opioid modulation on acute thermal nociception is located at the peripheral and supraspinal levels, and the opioid-potentiating effect is independent of the spinal noradrenaline increase produced by S1RA. [ABSTRACT FROM AUTHOR]

Abstract Recent findings have demonstrated new therapeutic functions of cardiotonic steroids, a process that is termed drug repositioning. Despite the confirmed anti-inflammatory effects of cardiotonic steroids, their clinical use has been discouraged due to toxicity related to inhibition of the Na+/K+ ATPase. A novel synthetic compound derived from digoxin, 21‑benzylidene digoxin (21‑BD), does not inhibit this enzyme. Herein, we evaluated the anti-inflammatory and antinociceptive effects and acute toxicity of 21‑BD. Murine (Swiss mice) models of paw oedema induced by carrageenan, acetic acid-induced abdominal writhing, and formalin and acute toxicity tests were used. Oral administration of 21‑BD (0.3 mg/kg) showed a significant and prolonged inhibition of paw oedema. Histological analysis demonstrated a reduction in inflammatory cells and expression of inducible nitric oxide synthase (iNOS) in footpads 6 h after administration of carrageenan. 21‑BD (0.3 mg/kg) also reduced the levels of tumour necrosis factor (TNF)-α 2 and 4 h after carrageenan. 21‑BD demonstrated antinociceptive activity, inhibiting abdominal writhes at all tested doses. However, in the formalin test, 21‑BD did not present antinociceptive activity. In the acute toxicity test, 21‑BD did not cause symptoms of toxicity or mortality. The present study demonstrated, for the first time, that 21‑BD is safe and exhibits a marked anti-inflammatory activity in acute local inflammation. This effect might be a consequence of its ability to inhibit the release of the PMN leucocyte-derived mediators, including TNF-α, and iNOS expression as well as its inhibitory effect on oedema and PMN leucocyte infiltration. Graphical abstract Unlabelled Image Highlights • 21‑BD exhibits marked anti-inflammatory activity in acute local inflammation. • 21‑BD inhibited paw oedema, leucocyte migration, iNOS expression and TNF-α levels. • 21‑BD does not exhibit pronounced antinociceptive activity. • In an acute toxicity test 21‑BD did not cause symptoms of toxicity or mortality. [ABSTRACT FROM AUTHOR]